ETI to launch project to develop Flettner rotor sails for ships; seeking at least 10% improvement in fuel efficiency
The Energy Technologies Institute (ETI) in the UK is seeking partners for a new project which it hopes will deliver fuel savings of at least 10% for large shipping vessels.
The Flettner Rotor Supply, Install and Commission Project will deliver a full scale demonstrator of Flettner Rotor technology on a large ocean going vessel which the ETI intends to source for the demonstration phase. Flettner rotors use a spinning cylinder to convert the force of the wind into thrust that helps propel the ship.
Flettner Rotors were developed in the 1920s by German engineer Anton Flettner; the Flettner rotor ship Buckau set sail in 1925, crossing the North Sea and then the Atlantic.
Flettner rotors use a spinning cylinder to convert the force of the wind into thrust to help propel the ship by using the Magnus effect, a commonly observed effect in which a spinning ball, or cylinder in this case, curves away from its principal path.
The Magnus effect observes that a revolving body moving relatively to a surrounding fluid—in this case, air—is subjected not only to drag, but also to lift. As the speed of the cylinder—spinning at right angles to the flow—increases, the pressure decreases on the side of the cylinder where the natural flow and the spin-induce flow combine. The decrease in pressure generates lift, and the lift increases as the surface velocity increases (per Bernoulli’s theorem).
The Magnus effect can generate more lift per unit of projected area than typical airfoil forms; the drawback is that 10-20% of the output power is required to spin the cylinder.
|Diagram of the Magnus effect applied to a ship, from Enercon. Click to enlarge.|
Flettner sail rotors have been demonstrated on ships since the 1920s, with at least two vessels trialing the technology in recent years. The ETI project will be the first demonstration on such a large vessel and is intended to provide valuable insights into real world fuel savings and ease of operation.
The Expression of Interest (EoI) aims to identify organisations capable of providing Flettner rotor technology for a large internationally traded ship. The ETI intends to use the EoI submissions to select a preferred technology provider capable of moving to the shaping phase of a full scale demonstration project.
Respondents will need to set out how their technology will deliver fuel savings of at least 10% and also how they would design, supply, install, commission, test and then support Flettner rotor vessel installation. At sea testing of the performance of the Flettner rotor installation will take place for at least one year after installation.
This is a project to design, develop and fit Flettner rotor blades—effectively mechanical sails—which will then be demonstrated and tested at sea in real life conditions. Studies have shown that Flettner blades could be beneficial in certain sea conditions around the world reducing fuel consumption in ships of between 7 and 15%. However, there has been insufficient full scale demonstration on a suitable marine vessel to prove the technology benefits. Successfully demonstrating this would make the technology more attractive to shipping companies and investors. The technology, if proved successful, could also be retrofitted to existing shipping fleets and play a significant role in reducing the fuel costs, so improving environmental impact.—Andrew Scott , manager for the ETI’s Flettner Rotor Supply, Install and Commission Project
The Expression of Interest for the Flettner Rotor Supply and Fit Project will close on 15 April 2016. The deadline for notification of intention to submit a proposal is 31 March 2016.
The ETI project is part of the marine element of its Heavy Duty Vehicles efficiency program.